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6 Commits

Author SHA1 Message Date
Cuong Manh Le
2c95e3a6a8 cmd/compile: use clearer error message for stuct literal
This CL changes "T literal.M" error message to "T{...}.M". It's clearer
expression and focusing user on actual issue.

Updates #38745

Change-Id: I84b455a86742f37e0bde5bf390aa02984eecc3c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/253677
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-09-12 08:31:49 +00:00
Matthew Dempsky
2a2423bd05 cmd/compile: more precise analysis of method values
Previously for a method value "x.M", we always flowed x directly to
the heap, which led to the receiver argument generally needing to be
heap allocated.

This CL changes it to flow x to the closure and M's receiver
parameter. This allows receiver arguments to be stack allocated as
long as (1) the closure never escapes, *and* (2) method doesn't leak
its receiver parameter.

Within the standard library, this allows a handful of objects to be
stack allocated instead. Listed here are diagnostics that were
previously emitted by "go build -gcflags=-m std cmd" that are no
longer emitted:

archive/tar/writer.go:118:6: moved to heap: f
archive/tar/writer.go:208:6: moved to heap: f
archive/tar/writer.go:248:6: moved to heap: f
cmd/compile/internal/gc/initorder.go:252:2: moved to heap: d
cmd/compile/internal/gc/initorder.go:75:2: moved to heap: s
cmd/go/internal/generate/generate.go:206:7: &Generator literal escapes to heap
cmd/internal/obj/arm64/asm7.go:910:2: moved to heap: c
cmd/internal/obj/mips/asm0.go:415:2: moved to heap: c
cmd/internal/obj/pcln.go:294:22: new(pcinlineState) escapes to heap
cmd/internal/obj/s390x/asmz.go:459:2: moved to heap: c
crypto/tls/handshake_server.go:56:2: moved to heap: hs

Thanks to Cuong Manh Le for help coming up with this solution.

Fixes #27557.

Change-Id: I8c85d671d07fb9b53e11d2dd05949a34dbbd7e17
Reviewed-on: https://go-review.googlesource.com/c/go/+/228263
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-04-21 20:49:34 +00:00
Matthew Dempsky
f346a4c44c test: add regress test for #27557
This commit just adds a regress test for a few of the important corner
cases that I identified in #27557, which turn out to not be tested
anywhere.

While here, annotate a few of the existing test cases where we could
improve escape analysis.

Updates #27557.

Change-Id: Ie57792a538f7899bb17915485fabc86100f469a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/197137
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-25 17:06:15 +00:00
Matthew Dempsky
606019cb4b cmd/compile: trim function name prefix from escape diagnostics
This information is redundant with the position information already
provided. Also, no other -m diagnostics print out function name.

While here, report parameter leak diagnostics against the parameter
declaration position rather than the function, and use Warnl for
"moved to heap" messages.

Test cases updated programmatically by removing the first word from
every "no match for" error emitted by run.go:

go run run.go |& \
  sed -E -n 's/^(.*):(.*): no match for `([^ ]* (.*))` in:$/\1!\2!\3!\4/p' | \
  while IFS='!' read -r fn line before after; do
    before=$(echo "$before" | sed 's/[.[\*^$()+?{|]/\\&/g')
    after=$(echo "$after" | sed -E 's/(\&|\\)/\\&/g')
    fn=$(find . -name "${fn}" | head -1)
    sed -i -E -e "${line}s/\"${before}\"/\"${after}\"/" "${fn}"
  done

Passes toolstash-check.

Change-Id: I6e02486b1409e4a8dbb2b9b816d22095835426b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/195040
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2019-09-16 15:30:51 +00:00
Matthew Dempsky
abefcac10a cmd/compile: skip escape analysis diagnostics for OADDR
For most nodes (e.g., OPTRLIT, OMAKESLICE, OCONVIFACE), escape
analysis prints "escapes to heap" or "does not escape" to indicate
whether that node's allocation can be heap or stack allocated.

These messages are also emitted for OADDR, even though OADDR does not
actually allocate anything itself. Moreover, it's redundant because
escape analysis already prints "moved to heap" diagnostics when an
OADDR node like "&x" causes x to require heap allocation.

Because OADDR nodes don't allocate memory, my escape analysis rewrite
doesn't naturally emit the "escapes to heap" / "does not escape"
diagnostics for them. It's also non-trivial to replicate the exact
semantics esc.go uses for OADDR.

Since there are so many of these messages, I'm disabling them in this
CL by themselves. I modified esc.go to suppress the Warnl calls
without any other behavior changes, and then used a shell script to
automatically remove any ERROR messages mentioned by run.go in
"missing error" or "no match for" lines.

Fixes #16300.
Updates #23109.

Change-Id: I3993e2743c3ff83ccd0893f4e73b366ff8871a57
Reviewed-on: https://go-review.googlesource.com/c/go/+/170319
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
2019-04-02 16:34:03 +00:00
Cherry Zhang
dbb1d198ab cmd/compile: fix loop depth of range expression in escape analysis
ORANGE node's Right node is the expression it is ranging over,
which is evaluated before the loop. In the escape analysis,
we should walk this node without loop depth incremented.

Fixes #21709.

Change-Id: Idc1e4c76e39afb5a344d85f6b497930a488ce5cf
Reviewed-on: https://go-review.googlesource.com/80740
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-11-30 13:45:18 +00:00